Heart Rate Variability and Heart Failure with Reduced Ejection Fraction: A Systematic Review of Literature

Introduction: Autonomic impairment is a hallmark of heart failure with reduced ejection fraction (HFrEF). While there have been studies on general values for each index of heart rate variability (HRV) analysis in HFrEF, a systematic review comprehensively examining representative values in HFrEF is lacking. Methods: We searched PubMed, Embase, and Cochrane databases to extract studies reporting representative values of HRV metrics in HFrEF. Results: A total of 470 HFrEF patients from 6 studies were included in the review. In general, time and frequency domains were abnormally lower in HFrEF, portending a worse prognosis. In HFrEF, the mean or median value of the standard deviation of NN interval, root mean square successive difference, pNN50, and low-frequency power/high-frequency power were 40 to 121 msec, 19 to 62 msec, 1.3 to 14%, and 1.00 to 1.73, respectively. Conclusion: In this systematic review, most HRV metrics were found to be calculated from 24- hour Holter recordings and were lower in HFrEF patients with poor prognosis.